In order to effectively use limited resources, there have been proposed techniques for converting various forms of energy into electric energy and extracting the electric energy. A technique for converting vibration energy into electric energy and extracting the electric energy is one of the techniques. For example, Patent Literature 1 described below discloses a power generating element of a piezoelectric type in which layered piezoelectric elements are stacked to form a piezoelectric element for power generation and the piezoelectric element for power generation is vibrated by an external force to perform power generation. Also, Patent Literature 2 discloses a power generating element of a MEMS (Micro Electro Mechanical System) structure in which a silicon substrate is used.
On the other hand, Patent Literature 3 discloses a power generating element of a type in which a hammerhead-type structure that supports a weight with a cantilever fixed at one end is used, the weight configuring a head portion is vibrated, and power generation is performed by a piezoelectric element for power generation disposed in a portion of a handle. Also, Patent Literature 4 discloses, together with the power generating element in which the hammerhead-type structure is used, a piezoelectric element in which a structure that supports a weight with a tabular bridge section bent in an L shape is used.
A basic principle of these power generating elements is to cause a cyclical bend in a piezoelectric element with vibration of a weight and extract an electric charge generated on the basis of stress applied to the piezoelectric element to the outside. If such power generating elements are mounted on, for example, an automobile, a train, a ship, and the like, it is possible to extract vibration energy applied during transportation as electric energy. It is also possible to attach the power generating elements to vibration sources such as a refrigerator and an air conditioner to perform power generation.